Operating outdrive in trailer mode in shallow water

Spyderweb

Ran across this discussion on another boating forum.  Poster wanted clarification on whether it was alright to raise outdrive all the way up when going through shallow water.  He posted this quote from Merc Manual:

"Never trim the drive unit UP/OUT using TRAILER switch while
boat is underway at engine speeds above 1200 rpm. Use extreme
caution when operating with drive unit raised. Severe
damage to the drive unit may result if unit is raised beyond the
gimbal ring support flanges at engine speeds above 1200 rpm."

I've been boating over 30 years, and the above is the same rule I've always followed.  I may back into a shallow beach area, or leave a shallow area at idle speed with drive fully up till I hit deeper water, and assumed I was OK.

The comments from the other posters did not agree.  They said either moving parts in drivetrain could grind away at inside of upper bellows, or there was too much strain put on drivetrain when fully up and in gear.  They essentially advised to be in gear only when within the "trim" limit".  This seems to contradict Mercs advice.

What say you guys?

RustyS

There was a recent thread eluding to the same topic.

I responded then, and will again standing by my long-time actions that agree with the quoted statement and you. We often are anchoring in shallow water around a natural sand bar. Coming and going across this area we are in full trailer trim. So long as you are at idling speed (below 1,000RPM in my opinion) and not holding wheel hard over in either direction there isn't any problem.

Have never dealt with any mechanical issues resulting from these actions. One in your column for it being ok.

And, we boat in the same water; I made it down the river 1 time this year. Wanted to get down there again, but season is closing in. Just up the river at Golden Crescent area of Lake O in Henderson Harbor.

Michael T

Never done it never will. Too worried about stress to components, lubrication, mechanical disadvantage if, by accident too much power is applied or there is an underwater strike. FWIW IMO.....far too much can go wrong. If I go in water so shallow that trim won't allow the drive to clear the bottom it's time for a dinghy or jet ski. Also, you could be sucking-up a $hit load of sand/gravel in that situation. 

212rowboat

I dont understand why either... A ujoint could easily fracture and that ends your day, just like that... Drives have to come off costing new bellows, and thats if youre lucky enough the upper wasnt damaged...  Or, tear a bellow... Better hope your batteries can run that bilge pump sufficiently enough long enough.  And all for being somewhere you shouldnt be to begin with? Doesn't make sense. If this is a constant concern, you've got the wrong boat. If it is an odd situation every once in a great while? You can take the precautions discussed and get by with it a few times most likely... 

Its your boat, sir.  Its a risk you're taking with your investment. 

aero3113

My last boat I used to trailer (21 foot regal). One day I launched it and it wouldn’t start, seemed like it was straining. I ran home to get a jump box and starter fluid while my girlfriend (now wife) waited on the boat. On the way to the house I got into a car accident (nothing major) with a town truck. It took me a while to get back to the boat,LoL! When I finally got back I was still having trouble starting the boat. Then I finally realized I forgot to put the drive down!! As so as I lowered the drive, she started right up. I think the angle of the U joint was causing so much strain it was lagging the engine. Lesson learned, will never do that again!! 

randy56

 Agree----They essentially advised to be in gear only when within the "trim" limit.
Agree with MT.
Agree with rowboat.
This could be a good poll. 

Willhound

Hmm. Interesting discussion. But thinking about it myself, and realizing not every hull is the same, we have to trim up this time of year to get out of the mouth of our harbour, water level is at about 28 - 30 inches max. At full trim up on the throttle switch my props are already cavitating and having been in the water when trimmed up I can say that if the leg hangs below the line of the keel it is maybe a couple of inches. If I used the trailer trim switch to trim further my props would mostly be out of the water and certainly higher than my keel, so what would be the point?
Granted, single engine 270, maybe it just sits different in the water.

GMSLITHO

I never had a need to do it where I boat ,but had to do it once on my 21 foot regal to get out of a spot one time  but I just kept it at idle speed that’s why it’s labeled trailer mode

Michael T

@GMSLITHO respectfully disagree - unless you are "kidding" - it's not labelled trailer mode to run it in shallow water it is labelled trailer mode to raise the drive skeg high enough to clear when you load it onto your .....

GMSLITHO

Sorry that’s what I meant,it’s labeled trailer mode for trailering 

rasbury

I would tend to agree with the folks with much more knowledge to the limits and design of these components. Otherwise it would be labeled shallow water trim and you would also raise to trailer!

reneechris14

looking at the edge of the u joint it self its ground down because it will touch. Now add some power(stress) to the combination. I would have to see a side view cut out to see if it comes close to the bellows, have done quite a few bellows in my day never noticed wear on the in side.

Michael T

@reneechris14 respectfully - also, if I remember correctly at "trailer trimmed" position there is no lateral protection for your drive(s) because they are past the drive guides that protect them. Yes, I would agree that you have said you would be going slow but even at slow speeds a big hull can exert a lot of force on a the drive should it get mired even in sand. IMO just too much money involved to gamble on wear and,or tear! 

aero3113

@Michael T that’s exactly what happened to my coworkers boat. He ran aground, tried to get out with trim all the way up. The drive was past the guides. He not only cracked the bell housing, he also cracked his transom assembly. 

212rowboat

a double cardan joint as used in an outdrive can take some strange angles... but when it leaves it's comfort zone it's sure to let you know with a catastrophic failure... 

@reneechris14 , that is what i was speaking of when bringing bellows into the conversation.. if a ujoint grenades, those bellows could take a good piece of it. otherwise, i don't think they near each other.  

randy56

At  some point, Trimming to high, your water pick-up can be out of the water. Then it can over heat, maybe destroy the impeller.  
I been at the boat ramp and seen guy's back in, Start the engine before letting the outdrive down, It make's a awful sound, kinda like a cat in a trap. Growning, squalling. in pain. 

Ian

I view trailer mode as that - to raise all the way up when hauling out or on the trailer. If you are that shallow you need to go to trailer mode, you shouldn't be there in my opinion.

Spyderweb

So i’m getting the impression (now from 2 sites) that you really should not put the drive in gear once it’s above trim mode.  In my earlier days of boating with young kids it was common for us to go shallow, and run at idle in trailer mode to leave a shallow area for a minute or 2.  Once kids got older and left we usually anchored in deep water.  Now i’ve got young grandkids and folks want to go in shallow again.  I will need to rethink how I do this, perhaps walking boat in and out of shallows, before engaging gear.

I guess i’m a little confused why Merc puts that statement in their manual about this being OK if under 1200 rpm’s.

mattie

randy56 said:

At  some point, Trimming to high, your water pick-up can be out of the water. Then it can over heat, maybe destroy the impeller.  
I been at the boat ramp and seen guy's back in, Start the engine before letting the outdrive down, It make's a awful sound, kinda like a cat in a trap. Growning, squalling. in pain. 

Did that once in shallows with our new Rinker in '08'. Wasn't familiar with the extra trailer mode detent button on the throttle. Alarm goes off pretty quick with an overheat. Shut it off & threw anchor until I figured out what I had accomplished.

JoeStang

Mine operates just fine in trailer mode at idle, the pickup is still under water (but barely). I dont like to do it, but have had to once or twice to keep the prop off the bottom and sucking sand.

JoeStang

icoultha said:

I view trailer mode as that - to raise all the way up when hauling out or on the trailer. If you are that shallow you need to go to trailer mode, you shouldn't be there in my opinion.

So someone with an outdrive should NEVER go into 2 foot of water? Here in Lake St Clair our average water depth is about 10 feet, and we have tons of bays that are sandy bottom, and very gradually get to 1-2' deep where you anchor and hang out. This year theres alot more water, but in years past even the canals have gotten so shallow they needed dredging mid-season.

I'll trust what Merc says is safe operation and use some common sense.

Ian

In my opinion - that's how I'd operate. We too have places that slope up with a sandy bottom you could beach onto but I have no desire to rub off more bottom paint than comes off normally by rubbing it on a sandy bottom. I'll drop anchor with 4-5' and swim over to the island if I need to. According to the specs we draw 22" drives up, 36" down and when we have periods where our pool level is low I raise a little accordingly but not even as high as trim limit. We all operate in different environments and if you are happy to do that, fine. 

rasbury

hey, the opinions are out there......probably if you have not installed a water impeller yourself, it's not as important to you. I can't afford to tear up an out drive so maybe more money = more willing to take the chance.

Spyderweb

@rasbury, no, never changed an impeller myself.  Until now, I'd never heard it was a bad practice to go slow in trailer mode (based on Merc manual saying it was ok).  In fact, a boat I had in the days when we used to go shallow a lot was a 1992 Bayliner 2452 bought new with a 5.0 Alpha 1 Gen II drive.  Had service manager check bellows each year.  Finally after 14 years he said it was time to change bellows, and he changed impeller at same time, not because it was bad, just a good idea.  I thought it was a good practice raising the drive because I was protecting the prop.  So from my experience, I had no reason to believe this was a bad practice.  That's why I check out these forums all the time.  Great way to learn.  

rasbury

Yep....and changing an impeller in an alpha 1 vs. a bravo iii is a hole different world...out drives sit different places on transoms and on these bigger boats, if I got mine out of the water I would never be able to see I was in trouble or hear anything until it was to late. FL is famous for shallow water and I just always figure if I'm so shallow I have to trim up that far, then well I'm just in to shallow water. To each their own! I could not describe what I have learned on this forum from past members as well as new. This is my main go to.